The present invention relates to a latch assembly for a passageway door lock and, more particularly, to a latch assembly for a door lock mounted in a passageway or panic exit, with the latch assembly including a latch that can be reliably retained in an unlatching position.
Locks mounted to doors in passageways or panic exits generally include horizontal type latches and vertical type latches. Vertical type latches include a top latch and a bottom latch. The latch bolts of the top and bottom latches should be retained by corresponding strikes in extended, latching positions when the door is closed and should be in retracted, unlatching positions when the door is being opened. The top and bottom latches generally move jointly such that one can not move without moving the other. However, in a case that the latch bolt of the top latch is moved to the unlatching position, due to the backlashes of the parts of the bottom latch after assembly, the latch bolt of the bottom latch could be further moved towards the latching position to a location interfering with the ground. As a result, the door can not be smoothly opened even though the latch bolt of the bottom latch is not in the latching position.
Thus, a need exists for a latch assembly for a passageway door lock in which the latch assembly can be reliably retained in the unlatching position to avoid interference to opening of the door.